There are many reasons to harvest and regenerate a woodland stand:
Most natural stands are composed of many tree species at various stages of growth. Woodlands constantly change as trees grow and die, moisture conditions vary, natural disturbances occur, people plant and cut trees, and so forth. Variations in stand age and origin, soil type, aspect, disturbance history, and species make every stand unique.
The various harvest and regeneration methods are not a discrete set of choices, but a spectrum of alternatives. At one end of the spectrum is the removal of all woody vegetation, leading to dramatic changes in soil temperature, moisture, and light conditions. These post-harvest conditions favor fast-growing species that need full sunlight such as aspen, jack pine, and red pine. At the other end of the spectrum is removal of single trees at scattered locations throughout the stand. This kind of harvest creates small canopy gaps favoring regeneration of shade-tolerant species such as sugar maple, balsam fir, and hemlock (where it exists). Between the two ends of the spectrum lies an infinite variety of treatments that vary by the number of trees harvested and how they are distributed around the stand.
Woodlands can be regenerated by natural or artificial means.